Morphology of Richards’ gland in the swarm-founding wasp
Protonectarina sylveirae (Hymenoptera, Vespidae)
Marjorie da Silva,
1
Fernando Barbosa Noll
1
and Johan Billen
2
1
Depto. Zoologia e Bot^anica, Universidade
Estadual Paulista, Crist ov~ao Colombo,
2265, 15054-000, S~ao Jose do Rio Preto,
SP, Brasil;
2
Zoological Institute, University
of Leuven, Naamsestraat 59, box 2466,
B-3000, Leuven, Belgium
Keywords:
Epiponini, exocrine glands, swarming, fifth
sternite gland
Accepted for publication:
27 May 2014
Abstract
da Silva, M., Noll, F. B. and Billen, J. 2015. Morphology of Richards’ gland in
the swarm-founding wasp Protonectarina sylveirae (Hymenoptera, Vespidae). — Acta
Zoologica (Stockholm) 96: 530–533.
Richards’ gland is known for the majority of Epiponini wasps, and despite few
experimental evidences, the taxonomic distribution in swarm-founder species
and the function of this gland remain rather unclear. This work presents a mor-
phological description of Richards’ gland in Protonectarina sylveirae. The gland is
formed by a cluster of class 3 cells underneath the anterior margin of the fifth
metasomal sternite, and a reservoir formed by the intersegmental membrane
between the fourth and fifth metasomal sternites where the secretion can be
stored. The secretory cells contain a branched end apparatus that carries the
secretory products towards the duct cell. Externally, the cuticle of the sternite,
where the duct cells penetrate, is characterized by modifications as scales with
very numerous pores. The presence of Richards’ gland according to the model
proposed by Samaca et al. 2013 in Protonectarina corroborates the single origin
of this gland in Epiponini. The occurrence of a Golgi apparatus and smooth
endoplasmic reticulum suggests pheromone production.
Marjorie da Silva, Laborat orio de Aculeata, Universidade Estadual Paulista,
Depto. Zoologia e Bot^anica, Crist ov~ao Colombo, 2265, 15054-000, S~ao Jose do
Rio Preto, SP, Brasil. E-mail: marjoriebio@gmail.com.
Introduction
Many aspects of social wasps’ life are mediated by exocrine
glands and their secretions, as dominance interactions, main-
tenance of the status of queen, food recruitment, search for
nest sites and defence, and reproductive behaviour (Downing
1991). Richards’ gland, which occurs between the fourth and
fifth metasomal sternites (Richards 1971), is known for the
majority of neotropical swarm-founding wasps, although its
development and structural organization may vary along spe-
cies (Jeanne and Post 1982; Jeanne et al. 1983; Smith et al.
2002). Following the standard classification of Noirot and
Quennedey (1974), this gland belongs to class 3, which is
made up by bicellular units, comprising secretory cells and
duct cells, the latter carrying the secretion to the outside sur-
face. The gland is associated with different types of cuticular
modifications in the region where the gland ducts open
(Jeanne and Post 1982; Samaca et al. 2013). The cells may
also be associated with a reservoir formed by an enlargement
of the intersegmental membrane (Jeanne and Post 1982;
Jeanne et al. 1983).
Richards’ gland was first described by Heselhaus (1922)
as a cluster of cells with their respective ducts, but as it was
Richards who called attention to the distribution of this gland
within the Vespidae (Richards 1971; 1978), West-Eberhard
(1977) called the modification at the base of the fifth sternite
‘Richards’ organ’ and afterwards, Jeanne and Post (1982) pro-
pose calling it Richards’ gland. Naumann (1975) proposed
that this gland secretes substances that are used to mark a trail
during the foundation of a new colony. This idea was later
confirmed by Jeanne (1981). Despite the experimental evi-
dence provided by Jeanne (1981) and Naumann (1975)
regarding the function of Richards’ gland, its taxonomic distri-
bution does not entirely match the distribution of swarm-
founder species (Smith et al. 2002), and the function of this
gland remains rather unclear.
As pointed out by Samaca et al. (2013), it would be inter-
esting to study Protonectarina wasps in more detail as Smith
© 2014 The Royal Swedish Academy of Sciences 530
Acta Zoologica (Stockholm) 96: 530–533 (October 2015) doi: 10.1111/azo.12089
Published for The Royal Swedish Academy of Sciences and The Royal Danish Academy of Sciences and Letters